The present invention relates to broadband linearly polarized antennas, being more particularly directed to dipole-type structures especially adapted (though not exclusively) for vertical polarization use and generally of biconical configuration.
The art is replete with innumerable dipole and other linear polarization antenna structures, including those of biconical shape, for producing wide band frequency operation, including, for example, omni-directional dipole structures of the type disclosed in U.S. Pat. No. 4,598,296 of common assignee herewith--such systems being useful for broadband communications, surveilance in the electromagnetic frequency spectrum and other applications. For certain of these uses, the general antenna requirements call for a voltage standing wave ratio (VSWR) of 2.5:1 or less over a very broad range of frequencies, a stable and moderately broad radiation pattern in the elevational plane of the antenna, and an omnidirectional radiation pattern in the azimuthal plane. Antennas that satisfy this requirement are generally fixedtuned structures and heretofore have involved relatively complex structures and impedance-matching and adjusting mechanisms; and there are extensive compromises in the breadth of elevational pattern and the degree of omni-directionality over very broad frequency bands, particularly embracing the several GHz frequencies, above and below.